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Topic: cheap amazon BCB AM filter.... (Read 629 times)

Just received my cheapo Chinese BCB AM filter from Amazon. The good news...it doesn't make the radio (Afedri SDR-net) deaf. The bad news...it doesn't completely deal with my intermod problem. I'm just going by eyeball right now, i'll try and do some direct comparisons +/- filter later this week or weekend and post some data. I do wonder if it would be possible to stick it between the antenna probe and the amplifier on my H800, however....logically it seems to me at least it would make sense to remove as much unwanted signal before the amp......

I agree, filtration before amplification will do wonders for signal purity and dynamic range. Also make sure you're not too high in front end gain in the sdr as well as having the noise blanker set too sensitive.

OK here's the clean +/- comparison i promised. No smoothing or noise reduction and all the auto-adjustments on the waterfall turned off. The top panel is filter in-line between the H800 and the Afedri, the middle panel is with the filter removed, and the bottom panel is the filter put back. The strong signal you see is 930 kHz. Not shown is the trace on the S-meter; baseline noise went from S2 with the filter on to S5-6 with it off.

So...for $20 bucks you can get some BCB relief. Does it solve all my intermod problems? No...perhaps in part because the BCB filter is working on the amplified signal from the antenna. Turns out the H800 has the preamp IN the antenna probe, and the little box is just the power supply for that.